Some image forming apparatuses such as copying machines and multifunction printers display, in accordance with image data processed according to the type of document and the setting conditions (e.g., print density, enlarging/reducing ratio, single-side printing/duplex printing, margin size), a preview of a single image to be printed or a combination of images to be printed.
Such a preview display is described, for example, in Patent Literature 1. In Patent Literature 1, a monochrome mode in which to copy a monochrome image having only one color (i.e., a black-and-white image such as a document or a monochrome image, such as a flier (leaflet), which has one color) and a full-color mode in which to copy a full-color image having at least two colors are included, and before an image to be copied in the monochrome mode and the full-color mode is recorded onto a sheet of paper, a preview of the image is displayed by a display device.
Further, for example, Patent Literature 2 discloses a technique for generating and displaying a preview image without performing edge enhancement on image data. In Patent Literature 2, RGB luminance signals read by a scanner are converted into CMY density (pixel value) signals by a logarithmic converter circuit. The resulting CMY density signals are processed through a masking/UCR circuit so as to be color-matched to the characteristics of a printer, processed by a circuit for performing image editing such as trimming, painting and enlarging/reducing (zooming) and a spatial filter circuit for performing a smoothing process on a printed-picture document, and then processed by a backward masking circuit for performing a conversion opposite to that performed by the masking/UCR circuit, an anti-logarithmic converter circuit for restoring the CMY density signals to the RGB luminance signals, a 3×3 matrix converter circuit for converting the RGB image signals from the color space of the scanner into the color space of the display device, and a gamma correction circuit for correcting the nonlinearity of the display device, whereby the preview of the image data is displayed by the display device.